Questions tagged [matching]
A matching (aka **Independent Edge Set**) in a simple graph is the set of pairwise non-adjacent edges i.e. no two edges have common vertex.
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questions
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a lower bound for the maximum fraction of matchings not containing an edge
I am trying to prove the following statement (from book, page 317):
Let $G(A,B,E)$ be a bipartite graph, where $A$ and $B$ are the two disjoint sets of vertices s.t. $|A|=|B|=n$. Let the number of ...
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1answer
23 views
Match unpaired points between two sets
I have two sets, let's call them C and T, of unpaired points, which could for example represent two types of cells. Hence, both points are drawn from the same underlying distribution, but the points ...
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1answer
41 views
Finding preferences for G-S algorithm (Algorithm Design Chapter 1 exercise 7)
I'm working on Algorithm Design (Kleinberg-Tardos) Chapter 1 exercise 7:
Some of your friends are working for CluNet, a builder of large
communication networks, and they are looking at algorithms for
...
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1answer
25 views
How are matchings a lower bound for an approximate vertex cover?
I am reading Algorithms by Dasgupta et al and they mention maximal matchings as approximations for vertex cover.
They mention that the 2-approximation ratio is a lower bound. How is a maximal matching ...
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9 views
Using bloom filters for high speed pattern matching in combination with Aho Corasick
I am implementing a new system for pattern matching in Intrusion Detection Systems for streaming data (network packets). I understand that bloom filters also produce false positives. Is there anyway ...
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48 views
Disjoint groups using maximum matching
In the 3-Path Packing problem, we are given an undirected graph $G$ and a parameter
$k \in \mathbb{N} \cup \{0\}$. We need to answer Yes/No if there exists a collection of $k$ vertex disjoint paths on ...
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37 views
Find an optimal matching in a complete graph
I have a complete edge-weighted graph with $n$ vertices (and therefore $n\cdot(n-1)/2$ edges). I want to find a complete matching (i.e., perfect matching) in which the quotient $sum_G/A_G$ is maximal, ...
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26 views
Stochastic matching with fewer queries
Given a graph $G = (V,E)$ and a probability $p \in [0,1]$ with which each edge is sampled from the graph $G$. The goal of the stochastic matching problem with fewer queries is to find a subgraph $H \...
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138 views
Maximum weight perfect matching in general graphs
Let $G(V,E)$ be a graph (not necessarily bipartite), where edge $e \in E$ has weight $w_e$ (non-negative real). Then one can write the LP relaxation for maximum weight perfect matching as follows
$$
\...
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73 views
Can somebody please explain what are these variables doing here?
I have this algorithm:
I understand overall what's happening here, we're shrinking the blossoms (odd cycles) to end up with a bipartite matching problem, and then opening them again to get a maximum ...
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1answer
167 views
calculating the string similarity of an optimal alignment
description of the algorithms behavior
I have two strings s1 and s2, with $len\_s1 <= len\_s2$. I would like to find the ...
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28 views
Is there an approximation algorithm for the three-person stable roommates problem?
While there's an algorithm for solving the stable roommates problem, I understand that the three-people-per-room version of that problem, sometimes called the "threesome roommates problem", ...
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1answer
25 views
Matching with specific cardinality
In a weighted graph $G(\mathcal{V},\mathcal{E})$ where $w(i,j)$ is the weight of the edge $(i,j) \in \mathcal{E}$. How can I find a maximum weighted matching with a specific size (i.e specific ...
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30 views
Gale-Shapley Stable matching where one man's preference list changes
Given $n>1$ women and men. Let $M$ be the stable matching given by the Gale-Shapley algorithm with men proposing. Is there a stable matching instance such that:
changing one man's preference list ...
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35 views
Computing a fractional matching of maximum product in a bipartite graph
Given a bipartite graph $(X\cup Y, E)$ with edge weights, it is easy to find a matching in which the product of weights is maximum: replace each edge weight with its logarithm, and find a matching in ...
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2answers
42 views
Maximum matching for general graph
I am studying the maximum matching problem and I was trying to understand why the classical augmenting path algorithm does not work for the general graph (i.e. for non bipartite graph) and you must ...
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1answer
53 views
Can't wrap my head around on building a suffix table for Boyer Moore
My resources were the following video, as well as this video.
Basically, in one of the videos they state that the good suffix table for the pattern "ABCBAB" is the following:
k
suffix
d2
1
...
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1answer
75 views
maximum cardinality weighted matching
I am looking for a reference for maximum cardinality weighted matching and the best running time algorithm for it.
Maximum Cardinality Weighted Matching: Given an undirected weighted graph $G(\mathcal{...
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1answer
158 views
Find optimal local alignment of two strings with restrictions
I have a homework question that I trying to solve for many hours without success, maybe someone can guide me to the right way of thinking about it.
The problem:
We want to find an optimal local ...
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47 views
Maximum cardinality matching of maximum weight
Given a graph, I want to find the matching with the maximum size in terms of edges, but among those matchings, given a real weight function on the edges, the one with the maximum weight. Is there an ...
1
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1answer
23 views
Concept of M-augmenting path to find a larger matching than $M$
I'm reading section 16.1 of the book, Combinatorial optimization, Polyhedra and efficiency by Schrijver. Here, he starts with a matching $M$ and describes a path $P$ that is $M$-augmenting if:
The ...
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1answer
28 views
splitting of people betwen groups with group prioritiy list per person
Looking for an algorithm for splitting a list of people (S) into groups (G), |S| <= |G|, more than one person wants to be in a certain group.
Every person has a monotone ranking from highest (most ...
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2answers
67 views
How difficult is this matching-like problem?
Let $A$ and $B$ be two sets of integers with $|A|>|B|$.
Given a map $f: A \rightarrow B$ and $i \in A, j \in B$, let us use the shorthand "$i$ is matched to $j$" if $f(i)=j$. I am ...
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1answer
191 views
Game on the graph with matchings
The game on the graph $G$ is defined as follows. Initially, the chip is located at one of the vertices (let's call it the starting one). The players take turns, on each move it is necessary to move ...
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30 views
Maximal vs maximum matchings
Let $M_1$ be an inclusion-maximal matching in $G$ (that is, there is no matching which strictly contains it), and $M_2$ a maximum-size matching in $G$. How to prove that $|M_2| \le 2|M_1|$?
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43 views
Independent sets into which all the vertices of the graph can be split
How to prove that if $G$ is an acyclic transitive digraph, then the least independent sets into which all vertices of G can be divided is equal to the size of the longest paths to $G$?
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26 views
Set of cycles in directed graph
I have a directed graph. How to find in it some set of cycles that are pairwise
do not intersect, but cover the entire set of vertices, if a cycle from one vertex is not considered a cycle, but cycle ...
1
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1answer
33 views
Maximum one-to-many matching
Let $G = (X+Y,E)$ be a bipartite graph and $k\geq 1$ an integer. A maximum $k$-matching is a subset of $E$ in which each vertex of $X$ is adjacent to at most $k$ edges and each vertex of $Y$ is ...
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1answer
52 views
Combinatorial Problem similar in nature to a special version of max weighted matching problem
I have a problem and want to know if there is any combinatorial optimization that is similar in nature to this problem or how to solve this special version of the max weight matching problem.
I have a ...
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47 views
Why did Hopcroft and Karp write $M_0, M_1, M_2, \cdots, M_i, \cdots$? (Hopcroft - Karp Algorithm)
I am reading “An $n^{\frac{5}{2}}$ Algorithm for Maximum Matchings in Bipartite Graphs” by Hopcroft and Karp.
Please see the image below.
Let $s$ be the cardinality of a maximum matching.
I think any ...
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1answer
192 views
Weighted Online Matching - randomized algorithms
Let's consider the edge weighted online matching problem.
The Vertices arrive online and reveal all their current edges and edge-weights $w_e>0$. The goal is to maximize the matchings weight. An ...
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1answer
47 views
Is there such a problem as b-Matching with different b values?
Consider a bipartite Garph $G=(L \cup R, E)$. Naturally, a b-Matching problem is to find a set of edges $M \subset E$, such that each node in $L$ and $R$ are adjuscent to maximum $b$ neighbors, and a ...
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0answers
22 views
How to generate a uniform random sample of unique vertex pairings from a undirected graph under constraint?
I'm working on a research project where I have to pair up entities together and analyze outcomes. Normally, without constraints on how the entities can be paired, I could easily select one random ...
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15 views
A request for literature on Matching your partner problem
I need reference for a good book (a title and an author will do) or reference on the web which explains the problem of matching procedures of suitable partners between several
males and females based ...
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1answer
87 views
Are these problems NP-Complete?
I got 2 decision problem that I need to answer if they are in P or they are NP complete:
1.Just like subset sum:
given the integers or natural numbers ${\displaystyle w_{1},\ldots ,w_{n}}$ does ...
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24 views
Stable matching with dynamic preference lists
I have a set $F$ of $n_1$ families, a set $C$ of $n_2$ children ($n_1<n_2$) and a set $M$ of feasible one-to-one matchings of the families with the children. All the children have the same ...
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25 views
Blossom Algorithm
I have noticed that in the blossom algorithm, we need to find the blossom while finding the augmenting path. What will happen if I just know there is a blossom in a graph and the contracted graph has ...
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66 views
Special case of stable marriage
I have an instance of the stable marriage problem in which the first side $S_1$ has $n_1$ agents and the second side $S_2$ has $n_2$ agents with $n_2$ is very big in comparison to $n_1$. In addition, ...
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0answers
96 views
Options for approaching stable marriage problem with unequally sized sets of elements/preferences
I am looking for an algorithm/code that will provide stable matching for two unequally sized sets of elements (clubs and students) with an unequal set of preferences. There is a large pool of students ...
3
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1answer
84 views
Selecting k rows and k columns from a matrix to maximize the sum of the k^2 elements
Suppose $A$ is an $n \times n$ matrix, and $k \ge 1$ is an integer. We want to find $k$ distinct indices from $\{1, 2, \ldots, n\}$, denoted as $i_1, \ldots, i_k$, such that
$\sum_{p, q = 1}^k A_{...
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20 views
Algorithm for b-matching on bipartite graph [duplicate]
I have a bipartite graph, where I want to assign nodes in Left set to Right set of nodes. There is a "b" constraint, which limits the maximum possible node degrees on the Right set.
Since it is a ...
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1answer
77 views
Best and Worst options in Gale Shapley algorithm for an agent
Please consider the figure below. I have to find the best and worst options for W. From the preference list of W, the best option for W is D but there is no matching of W with D in all the 6 options. ...
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2answers
124 views
An algorithm to find the closest match between 2 arrays of RGB pixel tuples
So I'm looking for a bit of an abstract algorithm and I'd appreciate any references to read up on. This is a bit tough to explain but I'll try my best.
Suppose we have 2 arrays of ...
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1answer
30 views
Problem with understanding two sided Matching Algorithm: maximium cardinality
I am trying to understand the maximum cardinality problem in the context of stable matching algorithm. I am reading the following article at the link:
A Two-Sided Matching Decision Model Based on ...
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36 views
Blossom's Algorithm or Maximal Matching [closed]
I am given a complete weighted graph and I need to make pairs among the vertices so that the sum of weights is maximum.
(If I have vertices $v1, v2, v3, v4$ and if I make pairs $(v1,v2)$ and $(v3,v4)$ ...
2
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1answer
671 views
one-to-many matching in bipartite graphs?
Consider having two sets $L$ (left) and $R$ (right).
$R$ nodes have a capacity limit.
Each edge $e$ has a cost $w(e)$.
I want to map each of the $L$ vertices to one node from $R$ (one-to-many ...
1
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1answer
446 views
How to find maximum matching edges in undirected tree
Let $B$ be an undirected tree with $|V|$ nodes given as adjacency list. I want to develop a greedy algorithm using pseudo code to find a maximal matching in runtime $\mathcal{O}(|V|)$.
My approach:
...
3
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1answer
39 views
Computing minimum partition of poset of $N$ intervals into chains in $o(N^{2.5})$ time?
Consider a set $P$ of $N$ intervals $\{I_i = (l_i, r_i)\}$ partially ordered according the standard interval order: $I_i < I_j$ iff $r_i \le l_j$.
I want to find a minimum cardinality partition of ...
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1answer
1k views
A problem with the greedy approach to finding a maximal matching
Suppose I have an undirected graph with four vertices $a,b,c,d$ which are connected as in a simple path from $a$ to $d$, i.e. the edge set $\{(a,b), (b,c), (c,d)\}$. Then I have seen the following ...
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String matching problem needed some explanation
This is a question from CLRS book. (Chapter 32, string matching, the question is the problem for the whole chapter, it's in the end of the chapter)
Let $y^i$ denote the concatenation of string y ...
